Dislocation networks in dispersion-strengthened aluminum produced by hot ex
trusion were investigated by transmission electron microscopy. Owing to the
close dislocation spacings, the weak-beam technique had to be employed. Bu
rgers vectors and line directions were determined in the as-produced state
and after annealing above the extrusion temperature. The dislocation networ
ks show remarkable regularity and can be grouped into three different types
according to their dislocation arrangement, spacings and Burgers vectors.
One type of the dislocation networks containing 60 degrees dislocations dis
appears during annealing and therefore is suggested to be responsible for t
he different mechanical properties of the material before and after heat tr
eatment. (C) 1999 Elsevier Science S.A. All rights reserved.